I had my 60 days free trial. Now I have a serial code from my university and when I try to use solid works a message that says, Activation transaction failed: Serial number not entitled to SOLIDWORKS 2021. Please contact your reseller. (3/0). Appear what is the problem?

Edu ​​​​​​3DEXPERIENCE ​​​​​​​SOLIDWORKS ​​​​​​